Dear Julie, 

I really don't know enough about this to offer up much on this topic, but since dex and other glucocorticoids are often given to treat asthma patients, it only stands to reason (doesn't it??) that the dex that your son was given helped to suppress his asthma symptoms.  I don't know the difference between respolin, respocort, or any of the other types of inhalers---as I mentioned we use albuterol and nasonex spray only sporadically---but if they are steroid based (respocort sounds like it is, from its name?), one would have to guess that their frequent use would have an affect on your son's levels.  Try searching the Pub-Med site (you probably have already.) I searched using the keywords "asthma steroids cushing."  There is enough there to, at least, come up with a list of good questions for your doctor on this topic.  Let us know what you find out!